Water sealed pumping system



P 19, 1967 HEV. SCHNABEL. JR 3,342,135

WATER SEALED PUMPING SYSTEM Filed Feb. 8, 1965 2 Sheets$heet l F IG. l

DISCHARGE JIB E ORIGINAL GROUND u u 5 1 WATER LEVEL f Q2 2 g! *7 I f L JH i: REDUCED GROUND 24 WATER LEVEL ,1

INVENTOR.

' HARRY sc ABEL, JR.

ATTORNEYS.

p 1967 v H. v. SCHNABEL, JR I 3,342,135

WATER SEALED PUMPING SYSTEM Filed'Feb. 8, '1965 2 Sheets-Sheet 2 FIG. 3 @A 2|8 2s 1%- F i i? i k P 43 EBB J: W v l3 1H L \Q) I J fima INVENTOR.

HARRY SCHNABEL, JR.

' ATTORNEYS.

United States Patent 3,342,135 WATER SEALED PUMPING SYSTEM Harry V. Schnabel, Jr., 5210 River Road, Bethesda, Md. 20016 Filed Feb. 8, 1965, Ser. No. 430,830 9 Cla'nns. (Cl. 103-5) ABSTRACT OF THE DISCLOSURE A water pumping system including a casing having a vacuum pump communicating therewith to cause water to flow into the casing from a plurality of well points also communicating therewith, and a water pump having an inlet in the casing for pumping water from the easing into a discharge pipe, one end of which communicates with the casing through the water pump and the other end of which communicates with the atmosphere, where in the casing is sealed when the water pump is deactuated by a Water seal in the casing and the discharge pipe, the difference between the water level in the casing and the water level in the discharge pipe representing the degree of vacuum in the casing.

This invention relates to pumping systems for lowering the level of ground water and more particularly to such systems utilizing a plurality of spaced well points connected by a header to which vacuum is applied to remove the ground water.

There are many situations where it is necessary or desirable to lower the water table or ground water level substantially below normal. Such may be accomplished, for example, to maintain building or canal excavations dry during the installation of foundations, linings or the like. A common current practice is to install a plurality of well points at spaced locations and to connect them at the top by a header pipe which leads to a combined water and vacuum pump. The water is drawn from the ground by the application of suction which causes it to rise in the well points, spill into the header pipe and flow to the pump from which it is passed through a discharge pipe to a disposal location. The instant the vacuum is lost in the system, pumping ceases. Since the vacuum is lost whenever the pump stops, it must be operated continuously even when the discharge is very slight, as for example when the ground water level is reduced to about the location of the well point inlets. To keep the pump operating continuously, it is usually necessary for an operator to remain on the job at all times. Indeed, the maintenance of continuous pumping is so essential that it is customary to have a second stand-by pump available.

Moreover, each pump must be of a capacity in excess of the normal anticipated demand. The maximum po tential volume occurs at the time of start-up. Since such maximum volume is generally far in eXCess of the actual volume when the water has been lowered to the anticipated level, the pump must be substantially oversize as well as run continuously. The result is both a large initial investment and a high operating cost.

Attempts have been made in the past to utilize separate pumps for applying the vacuum and removing. the accumulated water. Such systems have been unsuccessful, however, because whenever the discharge stops air enters the system through the discharge pipe of the water pump causing loss of vacuum.

To overcome the disadvantages of the prior art, it is an object of this invention to provide a pumping system for lowering ground water levels which incorporates separate water and vacuum pumps which may be intermittently operated as required without loss of vacuum.

A further object of the invention is to provide such "Ice a system wherein the pumps are automatically actuated and deactuated in accordance with demand.

In general the invention relates to a pumping system for removing ground water which comprises a header pipe, a plurality of spaced well points connected to said header pipe and having inlets below the normal ground water level, a water collection casing having a sealed upper portion connected to said header pipe and extending downwardly therefrom, a vacuum pump connected in fluid communication with said upper portion to cause ground water to flow through said well points and said header into said casing, 21 water pump having an inlet in said casing below said header, a discharge pipe connected to said water pump and exposed at its outer end to atmospheric pressure, said discharge pipe extending to a depth below said well point inlets to provide when said water pump has been deactuated a water seal which will retain in said upper portion a vacuum suflicient to cause said flow when the ground water is at any level from the ground surface to said well point inlets.

The invention having been generally described, several specific embodiments will now be discussed in detail with reference to the accompanying drawings in which:

FIGURE 1 is an elevational view partially in section of a pumping system in accordance with this invention;

FIGURE 2 is a view similar to FIGURE 1 of a. modified system; and

FIGURE 3 is a view similar to FIGURE 1 of a further modified system.

Illustrated in FIGURE 1 are a plurality of a conventional well points 11 which are normally sunk vertically into the ground to a depth not more than about 25 feet below the original water table or ground water level 12. Conventionally the well points 11 are spaced along a line or around a closed area depending upon the shape and size of the area in which the ground water levelmust be lowered. Each of the well points has at its. lower end an inlet 13 which conventionally is covered by a screen to exclude solid matter. The well points extend above the surface 14 of the ground and are connected by a header pipe 16 to a large water collection casing 18. In the embodiment of FIGURE 1 the casing 18 is sunk in the ground to a level substantially below the inlets 13 of the well points 11.

The top of the casing 18 is sealed to make it both water tight and air tight. A vacuum pump 21 is connected in fluid communication with the upper portion of the casing by means of an air line 22 which is preferably sufficiently long to preclude any possibility of water entering the vacuum pump. It will be understood that the connection between the vacuum pump and the casing 18 may be direct or may be through the header 16. In the usual manner the vacuum pump has a capacity to create a vacuum sufficient to cause water to flow upwardly in the well points 11 into the header 16 and then into the casing 18. In order to insure that the ground water level can be lowered substantially to the vicinity of the well point inlets 13, it is necessary that the pump be capable of applying a vacuum in feet of water at least equal to and preferably in excess of the depth of the well points 11.

Situated in the bottom of the casing 18 is a water pump 23 to which is connected the lower end of a discharge pipe 24. The upper end of the discharge pipe extends to the desired point of disposal of the water. The discharge pipe is thus exposed to atmospheric pressure at its upper end. The pump 23 has an inlet in the bottom of the casing 18 and when the pump is actuated the water is removed through the discharge pipe 24.

Preferably separate automatic means are provided to actuate and deactuate the pumps 21 and 23 as required.

The automatic means for actuating the pump 23 may include water level responsive switches 25 and 26 which are placed at first and second levels in the upper portion of the casing 18. The pump may be electrically operated with suitable conventional circuitry (not shown) controlled by the conventional water level responsive switches 25 and 26. When the water level in the casing 18 rises to the higher level of the switch 25 the pump 23 is actuated. When the level in the casing falls to the level of the lower switch 26 the pump is deactuated.

The automatic means for actuating the pump 21 may include pressure responsive switch 28 in the upper portion of the casing 18. When the pressure in the header pipe 16 and casing is reduced to a predetermined level of vacuum, the pump 21 is deactuated. When the pressure rises to a predetermined level, the pump 21 is again actuated. The system is sealed so that the vacuum will be retained and ground water will continue to flow even when the vacuum pump 21 is cut off. The water pump 23 will then continue to operate intermittently as required.

If desired, the automatic mechanism for controlling the starting and stopping of either or both of the pumps 21 and 23 may be eliminated. The operator would then manually start and stop one or both pumps in response to his own observations of requirements.

The vacuum pump 21 is sealed to prevent backflow of air into the system when it is stopped. If desired, as an additional safety precaution a valve may be installed in the line 22. Such valve may be a check valve to permit flow toward the pump only or may be automatically opened and closed when the vacuum pump is started and stopped, respectively.

Even when the ground water level is reduced to the point where the inlets 13 are exposed, very little air enters the well points because of the natural earth seal. Such air that does enter is easily removed by the vacuum pump.

When the water level in the casing falls to the level of the lower switch 26 and the pumps are deactuated, it will readily be recognized that the atmospheric pressure in the discharge pipe 24 will force the water level 27 in that pipe down to compensate for the pressure differential between the casing and the discharge pipe. The vertical distance between the water levels in the casing and the discharge pipe (the water head H shown in the drawings) is equal to the degree of vacuum (in feet of water) in the casing. Such vacuum should be at least sufficient to lower the ground water level substantially to the depth of the well point inlets. In other words, the vacuum, in feet of water, should be at least equal to and preferably greater than the depth in feet of the well point inlets below the header 16.

So long as water remains in the discharge pipe 24 the vacuum in the upper portion of the casing 18 will be sealed against the admittance of air through the pump 23. To insure the maintenance of such a seal, the discharge pipe 24 must extend to a depth below the minimum water level to be permitted in the casing equal to the maximum vacuum to be applied in feet of water. As stated, the maximum vacuum in feet of water should be at least equal to and preferably greater than the depth of the well point inlets 13 below the header 16.

As a minimum requirement, the discharge pipe must always extend to a depth below the inlets 13. Even if the water level in the casing 18 were never permitted to drop below the entrance into the casing from the header 16, the bottom of the discharge conduit 24 still would have to be below the well point inlets 13. Where the minimum level to be maintained in the casing 18 is the level of the switch 26, the discharge pipe 24 must extend to a depth below the switch 26 at least equal to and preferably greater than the depth of the well point inlets 13 below the header 16.

Stated differently, the depth of the discharge pipe 24 must be great enough to permit the column of water H exposed to the maximum vacuum to be of sufficient height to compensate for the pressure differential between the discharge pipe and the casing and still leave some water in the discharge pipe to provide the water seal. If there is no provision for such a column of Water, all of the water in the discharge pipe will be forced past the pump and the vacuum will be destroyed.

An alternative embodiment of the system is shown in FIGURE 2. This embodiment is identical to that of FIG- URE 1 except for the depth of the casing and the configuration of the discharge pipe of the water pump. The casing 118 has its bottom 119 positioned above the well point inlets 13. The discharge pipe 124 has a U-shaped lower portion 131 which extends to a depth below the well point inlets 13 to provide the water seal previously discussed. Thus, such depth must be a distance below the minimum level permitted in the casing, i.e. the level of the switch 26, equal to the maximum vacuum (in feet of water) to be applied. That maximum vacuum is at least equal to and preferably greater than the depth of the well points below the header.

The modification shown in FIGURE 3 is identical with that of FIGURE 2 except that the bottom 219 of the casing 218 extends down below the bottom of the lower U- shaped portion of discharge pipe 224. This arrangement enables a deep casing to be employed but with the water pump located substantially above the bottom of the casing.

Except as described above, the embodiments of FIG- URES 2 and 3 are identical in structure and function to that of FIGURE 1. The same principles apply with respect to the depth of the discharge pipe of the water pump.

The invention has been described With reference to certain specific embodiments. It will be understood that many other modifications may occur to persons skilled in the art without departing from the scope of the invention which is defined solely by the appended claims.

What is claimed is:

1. A pumping system for removing ground water which comprises a header pipe, a plurality of spaced well points connected to and extending downwardly into the ground from said header pipe and having inlets below said header pipe and below the normal ground water level, a water collection casing having a sealed upper portion connected to said header pipe and extending downwardly therefrom, a vacuum pump connected in fluid communication with said upper portion to cause ground water to flow through said well points and said header into said casing, a water pump having an inlet in said casing below said header, a discharge pipe connected to the outlet of said water pump and exposed at its outer end to atmospheric pressure, said discharge pipe extending to a depth below said well point inlets to provide when said water pump has been deactuated a water seal which will prevent admission of atmospheric pressure to said casing and will retain in said upper portion a vacuum sufiicient to cause said flow when there is ground water at any level from the ground surface to said well point inlets.

2. A pumping system according to claim 1 wherein said casing extends below said well point inlets.

3. A pumping system according to claim 2 wherein said water pump is located near the bottom of said casing.

4. A pumping system according to claim 1 wherein the bottom of said casing is above said well point inlets and said discharge pipe has a U-shaped section below said casing bottom.

5. A pumping system for removing ground water which comprises a header pipe, a plurality of spaced well points connected to said header pipe and having inlets below the normal ground water level, a water collection casing having a sealed upper portion connected to said header pipe and extending downwardly therefrom, a vacuum pump connected in fluid communication with said upper portion to cause ground water to flow through said well points.

. and said header into said casing, a water pump having an inlet 1n said casing below said header, automatic means.

to actuate and deactuate said water pump in. response to the rise and fall of water in said casing to predetermined first and second levels respectively, said second level being below said first level and above said water pump inlet, a discharge pipe connected to said water pump and exposed at its outer end to atmospheric pressure, said discharge pipe extending to a depth below said well point inlets to provide, when said water pump has been deactuated, a water seal which will retain in said upper por tion a vacuum sufficient to cause said flow when there is ground water at any level from the ground surface to said well point inlets, said depth of said discharge pipe exceeding the depth of said well point inlets by at least the distance between the tops of said well points and said second level.

6. A pumping system according to claim 5 wherein said casing extends below said well point inlets.

7. A pumping system according to claim 6 wherein said water pump is located near the bottom of said casing.

8. A pumping system according to claim 5 wherein the bottom of said casing is above said well point inlets and said discharge pipe has a U-shaped section below said casing bottom.

9. A pumping system according to claim 5 further com prising automatic means to actuate and deactuate said vacuum pump in response to the pressure in said upper portion, said vacuum pump being sealed to prevent loss of Vacuum in said upper portion.

References Cited UNITED STATES PATENTS 306,803 10/1884 Andrews 166-52 593,057 11/1897 Maury 166-52 1,190,268 7/1916 Dunn 103-5 1,255,130 2/1918 Burrell 166-52 1,323,146 11/1919 Barnett 103-5 2,433,408 12/1947 Tollefsen 10 3236 2,654,434 10/ 1953 Culleton 166-52 3,094,167 6/1963 Hine 103-236 3,187,719 6/1965 Jones 103-2i36 20 DONLEY I. STOCKING, Primary Examiner.

W. J. KRAUSS, Assistant Examiner. 

1. A PUMPING SYSTEM FOR REMOVING GROUND WATER WHICH COMPRISES A HEADER PIPE, A PLURALITY OF SPACED WELL POINTS CONNECTED TO AND EXTENDING DOWNWARDLY INTO THE GROUND FROM SAID HEADER PIPE AND HAVING INLETS BELOW SAID HEADER PIPE AND BELOW THE NORMAL GROUND WATER LEVEL, A WATER COLLECTION CASING HAVING A SEALED UPPER PORTION CONNECTED TO SAID HEADER PIPE AND EXTENDING DOWNWARDLY THEREFROM, A VACUUM PUMP CONNECTED IN FLUID COMMUNICATION WITH SAID UPPER PORTION TO CAUSE GROUND WATER TO FLOW THROUGH SAID WELL POINTS AND SAID HEADER INTO SAID CASING, A WATER PUMP HAVING AN INLET IN SAID CASING BELOW SAID HEADER, A DISCHARGE PIPE CONNECTED TO THE OUTLET OF SAID WATER PUMP AND EXPOSED AT ITS OUTER END TO ATMOSPHERIC PRESSURE, SAID DISCHARGE PIPE EXTENDING TO A DEPTH BELOW SAID WELL POINTS INLETS TO PROVIDE WHEN SAID WATER PUMP HAS BEEN DEACTUATED A WATER SEAL WHICH WILL PREVENT ADMISSION OF ATMOSPHERIC PRESSURE TO SAID CASING AND WILL RETAIN IN SAID UPPER PORTION A VACUUM SUFFICIENT TO CAUSE SAID FLOW WHEN THERE IS GROUND WATER AT ANY LEVEL FROM THE GROUND SURFACE TO SAID WELL POINT INLETS. 